Pushbutton switch assembly for keyboards including a bridging conductive, elastomeric diaphragm type contact

ABSTRACT

A pushbutton bears on its front face an elastomer conductive layer, conductive of electricity, of elastomer or elastic material and of limited area, which serves to close a circuit between two conductors of an array; moreover, between the latter and said layer there is arranged an insulating support exhibiting a pre-formed multiplicity of seats the positioning and arrangement of which are designed to be able to receive and hold each one ball or pellet or other equivalent intermediate member so that it can make contact on the one hand with the said conductors and on the other hand, when the pushbutton is depressed, with the said layer. Such an arrangement allows the use of coded combinations of contacts in a keyboard comprising a set of these pushbuttons.

United States Patent 1191 Arvai PUSHBUTTON SWITCH ASSEMBLY FOR KEYBOARDSINCLUDING A BRIDGING CONDUCTIVE, ELASTOMERIC DIAPHRAGM TYPE CONTACT [76]Inventor: Tibor Arvai, 14, rue de Berri, 75

Paris, France 22] Filed: July 18, 1972 21 A 110.; 272,780"

[301 Foreign Application Priority Data July 27, 1971 France 71.27453[52] 11.8. CI. 200/5 A, 200/159 B, 200/166 C, 1 200/D1G. 29 [51] Int.Cl. H01h 13/54 [58] Field of Search 200/1 R, 5 R, 5 A, 11 R, 200/11 DA,11 K, 16 C, 159 R, 159 B, 166 I I C, DIG. 29

[56] References Cited UNITED STATES PATENTS 3,534,194 10/1970 Speller200/166 C ox 3,665,126 5/1972 Gabor 200/5 A 1 June 18, 1974 3,699,29410/1972 Sudduth 200/159 B X FOREIGN PATENTS OR APPLICATIONS 1,200,8898/1970 Great Britain 200/1 1 DA Primary Examiner-James R. ScottAtt'0rney, Agent, or Firm-A. W. Breiner {57] 0 ABSTRACT A pushbuttonbears. on its front face an elastomer conductive layer, conductive ofelectricity, of elastomer or elastic material and of limited area, whichserves to closea circuit between two conductors of an array; moreover,between the latter and said layer there is arranged an insulatingsupport exhibiting a pre-formed multiplicity of seats the positioningand arrangement of which are designed tobe able to receive and hold eachone ball or pellet or other equivalent intermediate member so that itcan make contact on the one hand with the said conductors and on theother hand, when the pushbutton is depressed, with the said layer. Suchan arrangement allows the use of coded combinations of contacts in akeyboard comprising a set of these pushbuttons.

11 Claims, 5 Drawing Figures PATENTEDJUNIBIBM 3818 153 SHEET 3 (IF 3 Thepresent invention concerning electrical switches or like members refersmore particularly to devices with electrical contacts with pushbuttonscapable of forming a keyboard and suitable for establishing electricalconnections in ,a network or 'array of electrical conductors inaccordance with combinations predetermined and preferably marked on topof the actuating buttons of the corresponding devices.

Combinations of devices are already known for the same purpose, withcontacts arranged above an array of printed conductors, in which theplunger of the device, of pushbutton species, is provided with a smallportion of conductive elastomer so that pressing the button which isintegral with the plunger produces the application of the elastomerportion to the two conductors to be connected together which aresituated underneath, and the establishment of a circuit. Such devices,capable of forming a keyboard, are convenient to handle and inexpensiveto produce. At the same time, without completely exchanging anindividual switch device it is very difficult to modify its function orits coding, i.e., to make it connect two conductors different from thosefor which it was designed, because to do that it would be necessary tobe able to modify the position of the elastomer portion on the activepart of the plunger.

The principal object of the invention is to correct or improve upon theaforesaid by obtaining in individual contact devices in a keyboard ahigh flexibility of coding" and at the same time a great facility formodifying this coding, whilepreservin g in practice the advantages ofthe already mentioned known devices, namely, ease and economy in theirconstruction- In this respect use will still be made in the invention,in the part establishing contact, of portions of conductive elastomer,in associationwith other means aswill be explained.

Thus the invention relates to, as in the known previous art, to adevicewith electrical contacts actuated by pushbutton, in' which thepush-button bears on its front face a layer, conductive of electricity,of elastomer or elastic material and of limited area, which serves toclose a circuit between at least two predetermined conductors of anarray of electrical conductors, produced for example in printedcircuits, arranged facing the pushbutton; but in addition the saiddevice includes between the said elastic conductive layer and the arrayof conductors an insulating support exhibiting a pre-formed multiplicityof seats the positioning and arrangement of which are designed to beable to receive and hold each one ball (or pellet'or other equivalentintermediate member) so that it can make contact on the one hand withone of the said conductors and on the other hand, when the push-buttonis depressed, with the said layer.

This device lends itself conveniently, for example, to the seating oftwo conductive balls in positions chosen to establish a connection, andalso at least a third insulating ball to ensure stability. It issufficient to change the positions of the conductive balls to modify thecoding of the switch. It is easy to construct a keyboard of suchswitches.

The invention will be better explained and understood by referring byway of non-restrictive example to the following description and to theattached drawings in which:

FIG. 1' is an axial section through a contact device in accordance'withthe invention, in the up position (not making contact);

FIG. 2 is a similar section of the same device in the down position(making contact);

FIG. 3 shows how the ball seating plates can be arranged above theconductors, and 1 FIGS. 4 and 5. illustrate example of keyboardsconsisting of contact devices in accordance with the inventlon.

In FIG. 1 the body of thehousing of the contact device is seen at 1, at2 the push-button bearing at its end an elastomer layer 3 which here hasan annular shape concentricwith the axis A-A of the housing. The support4 bears on its upper face the array 9 (FIG. 3) of printed circuits. Aplate 5 fitted into the body 1 is applied-against the slab 4 by means ofscrews 5a (see FIG. 3). An axial coil spring 6 is placed between thepushbotton and the plate.

The plate 5 exhibits a series of seats X X X E, in the form of holesopen top and bottom, in which balls 7 can be placedwithout going rightthrough, the hole being necked in at the bottom at 7a. The position ofeach of these seats is chosen to be directly on top of one of theconductors 9, the seats being distributed round the axis AA as seen inFIG. 3.

In addition the annular ring 3 of conductive elastomer is fastened tothe end of the push-button 2 by means of projections 2a bornebythe'latter, which simplifies putting it in position, ensures itsretention but still enables it to be conveniently exchanged. Again, inthe end face of the push-button facing each ball 7 slight hollows 2bhave been formed.

For example, two balls 7 will be used, of a material conductive ofelectricity at least on the surface, such as metal (steel) silvered orgilded on the surface. It will be possible to have only two such balls;a third ball of insulating material, for example, glass, in a suitablyplaced seat, can ensure stability. The other seats can be unfilled orcontain insulating balls as well.

When the push-button is pressed as by force 8 (FIG. 2), the conductiveballs 7 which are each in contact with one of the conductors 9, arecontacted by the ring 3. Good contact is obtained as a result of hollow2b which when the push-button is pressed lets the elastic material ofthe ring deform freely and adopt the shape of the ball. In this way thetwo conductors of the array 9'are connected together through the twoballs 7 and the ring 3. g

The hole E is designed to come over the top of the voltage supplyconductor (one pole of the voltage), the return circuit being made byany one (or a number) of the other conductors back to the other pole ofthe supply voltage. There can in fact be more than two conductive ballsin action, namely a predetermined limited number of these balls, so asto connect together more than two conductors. Advantageously the ball 7in the hole E can be a little smaller (for example, 0.1 mm

, smaller) than the others, so as to effect good contact simultaneouslyfor a number of conductors with a delay.

It can also be seen that the assembly is designed so as to be easilydismantled and so that the combinations of connections can be .modifiedto choice in each contact device by moving the positions of the balls.

This system is thus very flexible, In addition, each of the contactdevices can be placed atany point along the path of the array ofconductors. In FIG. 3 it is seen that the positions of the plate (plate5 has'a standard form for all the contact devices) are reversed for thetwo devices shown; that is due to the path of the array of conductors,bent back on itself. On thisprinciple complete keyboards can be producedfor all combinations to be effected. FIGS. 4 and 5 show examples ofthese executions. The tops of the contact devices (1a, lb,'etc...) areshown bearing symbols representing the combinations.

Over the top of the contact devices a flexible filmor fabric canadvantageously be provided .which ensures air-tightness of the devices,the bodies of which exhibit on top an appropriate hollow shape not toobstruct operation, the fabric bending in as seen in FIG. 2. The film orfabric can be transparent and in this case the indication of the symbolsareseen through it, engraved or otherwise marked on the faces of thepush-buttons;

or else the film or fabric itself, not necessarily transpar-v ent, bearsthe symbols printed on it, which are not es-.

sentially marked on the said faces of the buttons. The embodimentsdescribed are only examples of the invention and that it would. bepossible to modify them, especially by substitution of technicalequivalents, without thereby departing from the scope of the invention;for example, the balls can be replaced by pellets or other equivalentintermediate members.

I claim:

1. A contact device having a rest position and an operative position andcomprising an elastic layer conductive of electricity and of elasticmaterial, a pushbutton for actuating said contact device provided with.

spring means for repelling said push-button in said rest position andretention means for maintaining said layer on the inner operative faceof said push-button, an insulating plate having a network of electricalconductors affixed on its surface facing the operative face of saidpush-button at a distance in the rest position, a plurality of tinysolid elements, some of which are conductive of electricity and eachbeing in contact with a corresponding one of said conductors by theirside opposed to said push-button, an insulating support which is distantfrom said layer in rest position, interposed between said layer andnetwork of conductors and provided with a predetermined multiplicity ofseats, each retaining therein one individual element, each of saidelements corresponding to an individual conductor so that saidconductive element in contact with one conductor can also on itsopposite face make contactwith said layer when said push-button isdepressed in operative position contrary to said spring means.

2. A device as in'claim l, in which said solid elements are balls ofmaterial conductive of electricity at least at the surface and inpredetermined limited number are seated in seats of which the positionsare predetermined in order to effect a coded combination of connectionsbetween conductors which can vary as a function of these positions. a

3. A device as in claim 2, in which the said limit number is two.

4. A device as in claim 2, in which one of said balls comes into'contact with one of said conductors connected to one pole of the supplyvoltage and other conductors are connected to theother pole, said one ofthe balls being slightly smaller than the other balls.

5. A device as in claim 1, in which in certain of the seats aninsulating element is seated,-for example of glass.

6. A device as in claim I, in which said elastic or elastomeric layerhas an annular shape encircling the axis of said push-button. I

7. A device as in claim 1, inwhich said means-of retention comprise atthe end of said push-button roughnesses which can penetrate the materialof said elastic layer.

8. A device as in claim'l, in which said face of the end of saidpush-button is provided opposite the positions of said seatswith hollowsenabling slight flexing of said elastic layer into them.

9. A device as in claim 1, in which said support has a plate shape andin which the different seats for said solid elements are distributedround the axis of said push-button.

10. A combination of contact devices'as in claim 9, in which the saidcontact devices are at least partially joined side-by-side to form akeyboard with said array of conductors following a path passingunderneath each of said devices, said support-plate being suitablyorientated and the positions of said balls being selected to effect adistinct combination characteristic of each individual device.

11. A contact device as in claim 1, in which a flexible fabric coversthe top of each body of said device, which has an appropriate hollowshape, ensuring its airtightness.

1. A contact device having a rest position and an operative position andcomprising an elastic layer conductive of electricity and of elasticmaterial, a push-button for actuating said contact device provided withspring means for repelling said push-button in said rest position andretention means for maintaining said layer on the inner operative faceof said pushbutton, an insulating plate having a network of electricalconductors affixed on its surface facing the operative face of saidpush-button at a distance in the rest position, a plurality of tinysolid elements, some of which are conductive of electricity and eachbeing in contact with a corresponding one of said conductors by theirside opposed to said push-button, an insulating support which is distantfrom said layer in rest position, interposed between said layer andnetwork of conductors and provided with a predetermined multiplicity ofseats, each retaining therein one individual element, each of saidelements corresponding to an individual conductor so that saidconductive element in contact with one conductor can also on itsopposite face make contact with said layer when said push-button isdepressed in operative position contrary to said spring means.
 2. Adevice as in claim 1, in which said solid elements are balls of materialconductive of electricity at least at the surface and in predeterminedlimited number are seated in seats of which the positions arepredetermined in order to effect a coded combination of connectionsbetween conductors which can vary as a function of these positions.
 3. Adevice as in claim 2, in which the said limit number is two.
 4. A deviceas in claim 2, in which one of said balls comes into contact with one ofsaid conductors connected to one pole of the supply voltage and otherconductors are connected to the other pole, said one of the balls beingslightly smaller than the other balls.
 5. A device as in claim 1, inwhich in certain of the seats an insulating element is seated, forexample of glass.
 6. A device as in claim 1, in which said elastic orelastomeric layer has an annular shape encircling the axis of saidpush-button.
 7. A device as in claim 1, in which said means of retentioncomprise at the end of said push-button roughnesses which can penetratethe material of said elastic layer.
 8. A device as iN claim 1, in whichsaid face of the end of said push-button is provided opposite thepositions of said seats with hollows enabling slight flexing of saidelastic layer into them.
 9. A device as in claim 1, in which saidsupport has a plate shape and in which the different seats for saidsolid elements are distributed round the axis of said push-button.
 10. Acombination of contact devices as in claim 9, in which the said contactdevices are at least partially joined side-by-side to form a keyboardwith said array of conductors following a path passing underneath eachof said devices, said support-plate being suitably orientated and thepositions of said balls being selected to effect a distinct combinationcharacteristic of each individual device.
 11. A contact device as inclaim 1, in which a flexible fabric covers the top of each body of saiddevice, which has an appropriate hollow shape, ensuring itsairtightness.